1. Field of the Invention
This invention relates to an overload protecting device in a snow removing machine, which has a simplified structure for protecting a power transmission path extending between a prime mover and an auger of the snow removing machine from encountering an overload.
2. Description of the Related Art
Various self-propelled snow removing machines have hitherto been proposed. A typical example of such machines is disclosed in Japanese Utility Model Publication No. SHO-51-34111.
The disclosed snow removing machine is comprised of an engine, a first pulley coupled to an output shaft of the engine, a belt stretched over between the first pulley and a second pulley, a rotating transmission shaft extending forwardly of the second pulley, a rotating auger shaft coupled to a forward end of the rotating transmission shaft via a gear case, and an auger mounted to the rotating auger shaft.
In the aforementioned snow removing machine, the auger is apt to bite a lump of ice or stone during a snow removing work to interrupt rotation of the auger, causing the power transmission path between the engine and the auger to encounter an overload. It is, therefore, desirable to remove such an overload state. However, employment of a complicated device or mechanism for removing the overload state undesirably results in an increase in the manufacturing cost.
It is therefore an object of the present invention to provide a structurally-simplified overload protecting device in a snow removing machine for preventing a power transmission path extending between a prime mover and an auger of the machine from encountering an overload.
According to an aspect of the present invention, there is provided an overload protecting device assembled in an auger transmission of a snow removing machine which comprises a worm wheel meshing with a worm formed on an input shaft of the auger transmission, a cylindrical member engaging with the worm wheel to be rotatable relative thereto and fixedly coupled to an auger shaft for non-rotational relationship, a disk located adjacent to the worm wheel for restricting a rotating angle of the cylindrical member and having a plurality of wheel-sided projections facing a plurality of wheel-sided protruded segments formed at a side wall of the worm wheel, detecting means for detecting movement of the disk toward a side thereof when the wheel-sided projections ride on the wheel sided protruded segments responsive to rotation of the worm wheel and the cylindrical member relative to one another, prime mover stopper means for forcibly stopping operation of a prime mover responsive to a signal delivered from the detecting means, and a resilient member urging the disk against the worm wheel, wherein a power transmission path between the prime mover and the auger shaft is prevented from encountering an overload.
With such a structure, when the auger shaft encounters a torque exceeding a given value, the worm wheel and the cylindrical member are enabled to rotate relative to one another, thereby allowing the wheel-side projections of the disk to ride on the wheel-side protruded segments of the worm wheel to cause the disk to be moved in a direction opposite from the worm wheel. Such movement of the disk is detected by the detecting means, thereby enabling the operation of the prime mover to be forcibly stopped in response to a signal produced by the detection means. Accordingly, by forming wheel-side protruding segments on the conventional worm wheel and by forming wheel-side projections on the disk while employing a commonly used switch as a detecting means and a relay as a prime mover stopper means to interrupt the ignition circuitry of the prime mover, it is possible for the power transmission path of the snow removing machine to be protected from encountering the overload in a simplified structure.
In a preferred form, the case of the auger transmission is provided with a case-side protruding element, while the disk is provided on a rear surface opposite from the surface formed with the wheel-side projecting element with a plurality of case-side projections to restrict rotation of the disk relative to the case by allowing the case-side projections to engage with the case-side protruding element. In this arrangement, when the rotation of the worm wheel is interrupted under a condition where the wheel-side projections ride on the wheel-side protruded segments, the auger, which is mounted to the auger shaft, is manually rotated in a clockwise direction, thereby causing the case-side projections of the disk to be brought into abutting engagement with the case-side protruding element of the case to stop rotation of the disk. When this occurs, the worm wheel is enabled to rotate to cause the wheel-side projections of the disk to slide across the wheel-side protruded segments. With such movement, the disk is enabled to restore its original position, releasing the detecting means to thereby allow the prime mover to be restarted up. Accordingly, it is possible for the overload protecting device to prevent an undesirable condition wherein the wheel-side projections of the disk remain in the riding condition over the wheel-side protruded segments in a simplified structure and in an easy fashion.
It is desirable that the aforementioned wheel-side projections and the case-side projections are oriented in a clockwise rotational direction of the auger shaft. That is, when assembling the disk, if the wheel-side projections and the case-side projections of the disk are oriented in the same rotational direction of the auger shaft during the snow removing work, it is possible to effectively prevent erroneous assembling of the disk and, further, by forming the wheel-side projections and the case-side projections in the same orientation, an easy fabricating step for the disk is obtained.
In a preferred form, the resilient member comprises a waved leaf spring made of an annular thin sheet formed by a waved-profile bending process. That is, the presence of the resilient member made of the waved leaf spring is effective for reducing a longitudinal space for receiving a spring to a smaller value than that required in, for example, a coil spring, thereby contributing to a miniaturization of the auger transmission.